In the German patent DE 199 06 287 A1 a procedure to operate a particle filter of an internal combustion engine is described, which from time to time is regenerated. The regeneration occurs as a function of a measurement for the degree of depletion of the particle filter. If the sooty particles are not conditioned, the particles oxidize from a temperature of about 550° forward. The required ignition temperature of the particles can, for example, thereby be achieved, when a reagent substance, for example, non-combusted hydrocarbons, is introduced into the exhaust gas area of the internal combustion engine. This reagent substance reacts exothermally on a catalytic surface area and thereby raises the exhaust gas temperature.
In the German patent DE 101 13 010 A1 a procedure is described to diagnose an exhaust gas treatment system disposed in the exhaust gas area of an internal combustion engine, in which the temperature of the exhaust gas is measured in each case by a sensor in front of and after the exhaust gas treatment system. The diagnosis is based upon an expected increase in temperature of the exhaust gas, if the exhaust gas contains non-combusted hydrocarbons, which react exothermally on a catalytically active surface. An error free exhaust gas treatment system is present, if an expected increase in the temperature measured behind the exhaust gas treatment system occurs due to an increase of the proportion of non-combusted hydrocarbons in the exhaust gas of the internal combustion engine. The diagnosis only occurs then, as long as provision is made for the introduction of the non-combusted hydrocarbons. Furthermore, the diagnosis only occurs, if the temperature measured in front of the exhaust gas treatment system does not change considerably within a certain time period during the introduction of the non-combusted hydrocarbons.
In the German patent DE 44 26 020 A1 a procedure is described, in which the functional capability of a catalytic converter disposed in the exhaust gas area of an internal combustion engine is monitored. The monitoring is implemented by using the temperature increase, which occurs by way of the exothermic conversion of exhaust gas components, which can be oxidized. Two temperatures are ascertained, whereby the first temperature is based upon the measurement of the temperature down stream from the catalytic converter, and the second temperature is calculated with the help of a model.